Epidemiological studies suggest that prenatal exposure to marihuana may result in perinatal hypoxia and postnatal behavioral anomalies such as altered visual responsiveness and increased tremors. Controlled studies in animals, however, indicate that neither marihuana nor delta-9-tetrahydrocannabional (the principal psychoactive ingredient in marihuana) is behaviorally teratogenic. One reason for the discrepancy between the human and animal studies is that in many cases, the mothers studied in the epidemiological reports used other substances such as tobacco, alcohol, etc. These substances may have interacted with marihuana to produce the reported effects. In the studies with animals, these sources of confounding were eliminated. The aim of this proposal is to determine if the combined exposure to marihuana and other substances will result in a greater impairment in subsequent behavior compared to exposure to marihuana alone. The studies to be conducted will use the "animal model" developed over several years in our laboratory with respect to prenatal effects of harihuana. This model includes control procedures for drug-related undernutrition via a "pair-feeding' technique and for residual drug effects on maternal behavior/lactational-performance via a postnatal surrogate-fostering procedures.